Variable pressure vent control



Feb. 28, 1950 J. F. SEBALD VARIABLE PRESSURE VENT CONTROL Filed Sept. 11, 1948 Ill:

JOSEPH F. SEBALD IN V EN TOR.

Patented Feb. 28, 1950 1 VARIABLE PRESSURE VENT CONTROL Joseph F. Sebald, Bloomfield, N. J., assignor to Worthington Pump and Machinery Corporation, Harrison, N. J a corporation of Delaware Application September 11, 1948, Serial No. 48,915 4 Claims. (Cl. 257-42) This invention relates generally to the venting of air and non-condensible gases from feedwater heaters and deaerators and, in particular, to a venting control for vent condensers subject to variable pressure operation.

In a feedwater heater, deaerator, or the like, it is highly desirable that the amount of air and other non-condensible gases contained in the water fed to these systems be reduced to a minimum, as the presence of oxygen and other gases will operate to interfere with the efficiency of the said systems. Also, pitting, and corrosion will result on the various metal surfaces due to oxygen attack.

In operation, this is accomplished by bringing the raw water fed into the feedwater heaters, deaerators and similar systems to its varporization temperature (related directly to the operating pressure) andagitating the water and vapor to aid in releasing the air and other non-condensible gases.

Thereafter removal of these gases is necessary as increased concentration will interfere with the further removal of gases from the raw water. Usually to accomplish this, a quantity of steam is vented from the unit in combination with the released gases. This may be done directly to atmosphere in which event therewill be considerable loss of steam or, it may be vented through a surface condenser known as a vent condenser in which make up water mayv be used as the coolant to recover a portion of the latent heat of vaporization of the steam and at the same time provide means for venting the gases to atmosphere.

The amount of steam passing to the vent condenser varies with load and plant conditions. The next step is venting the uncondensed steam, air and non-condensible gases from the vent condenser to atmosphere. This may be done manually or by some type of automatic control. The usual thermostatic controls are applicable only to those systems which operate under substantially constant steam pressure and temperature. Where the pressure variations are of high magnitude resulting in wide changes in temperature, thermostatic controls cannot be used, without some provision for manual adjustment of the temperature range under which the thermostat must operate. Such necessary manual adjustment therefore eliminates the use of the thermostatic control as an automatic device.

An object of the present invention is to provide a vent control which will maintain adequate venting at all times without excessive loss of steam at the high pressureconditions with ample venting available for the low pressure conditions.

A further object of the present invention is to provide a venting arrangement for variable pressure operation so as to preclude the necessity of manual adjustments as the pressure varies from time to time in the operation of the systems.

With these and other objects in view, as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts which will be first described in connection with the accompanying drawing, showing a variable pressure vent control of a preferred form embodying the invention, and the features forming the invention will be specifically pointed out in the claims.

In the drawings:

The single figure is a diagrammatic sketch of the apparatus partly in section.

Referring more particularly to the drawing, a vent condenser I is shown representing any conventional type of vent condenser utilized'with feedwater heaters, deaerators and the like.

The vent condenser I will have an inlet point for receiving steam and released gases, a venting outlet 2 to allow the uncondensed steam, air

and non-condensible gases to pass out of the vent condenser, and vent piping 3 for leading off the uncondensed steam, air and non-condensible gases.

A manually operated auxiliary vent valve 4 is connected to. the vent piping 3 and is used for starting up and shutting down the feedwater heater, deaerator or other system. While a globe valve is shown, any conventional type of valve which will perform the same task may be utilized, it being understood that except for starting up and shutting down the system this valve will remain closed.

A pressure reducing valve 5, shown in the drawing, is also connected to the vent piping 3 at a point more distant from the vent condenser than theauxiliary vent valve 4. This reduced pressure valve is utilized for receiving a varying or high pressure at the inlet or upstream side and automatically delivering a constant reduced pressure to the outlet or downstream side.

In the pressure reducing valve 5, valve ports 6 and 6' receive the double port balanced inner valves I and I. The valves 1 and I are mounted on valve stem 8, which in turn is held in position by the valve guide 9. A spring is mounted to coact at one end with the valve stem 8 being held in position at the valve stem end of the spring by a threaded adjustment nut connector H. The other end of the spring I0 is held in position by and coacts with a diaphragm member i2.

The diaphragm member l2 divides a chamber l3 so that part of the chamber is under atmospheric pressure and the remainder of the chamber is under a substantially constant pressure maintained by the valve regulated by a pilot line H.

Pilot line I4 is connected between chamber 13 and the vent piping 3 on the downstream side of the valve 5 and operates to transmit whatever pressure is in the downstream side of the valve 5, to the line pressure side of chamber I3. To

restrict flow through vent piping 3, a cap l5 with an insert orifice I6 is provided. The insert orifice I6 is provided with an opening I! of predetermined cross sectional area, which serves to provide the vent piping with an opening to atmosphere or other low pressure receiver. This orifice I1 is to be sized so that it will pass the required volume of vented vapor and gases at a constant differential pressure. The orifice would be calculated with an upstream pressure somewhat below the minimum operating pressure in the heater or deaerator and sized to take care of the venting requirement of the system.

There would be some variation in the amount of gas vapor mixture which the orifice would pass ,at constant total heat is a relatively minor variation in flow rate and may be compensated for in the invention herein by slightly oversizing the orifice for the minimum superheat condition.

In o eration, the steam, air, and non-condensible gases will be vented from the vent condenser through the vent piping 3 to the pressure reducing valve 5, at an initial pressure which will vary from the lowest operating pressure to a maximum operating pressure.

This initial pressure is received at the inlet or upstream side of the reducing valve 5 and is converted by the valve to a pressure on its outlet or downstream side which will be a constant predetermined as less than the minimum value that the initial pressure may be, yet greater than atmospheric pressure.

To obtain the required fiow at this constant pressure, the orifice I'I operates in combination with the pressure reducing valve 5. As the steam, air, and non-condensible gases pass through the valve they must overcome the resistance of the spring l0, coacting with the diaphragm l2. The tension of the spring I0 is adjusted by the threaded adjustment connector I i, while the force exerted on the diaphragm against the spring is regulated by the pilot line [4, transmitting the pressure from the downstream side of the valve 5.

As the pressure in the system increases or decreases the pressure passing through to the downstream side will tend to increase and decrease proportionately. Due to the sizing of the orifice a back pressure will develop which will be immediately transmitted by the pilot line H! to the varying pressure side of the chamber l3. This, in turn, will cause the diaphragm l2 to fluctuate and exert less or more pressure on the spring ID. The spring [0, in turn, causes the valve stem 8 to move which in turn causes valves 1 and 1' to increase or reduce the amount of opening at the valve ports. Thus, if the pressure on the downstream side is high it will be reduced, and vice versa if it is low, which results in a more or less constant pressure on the downstream side of the valve 5.

The orifice opening to atmosphere will then be able to vent the required volume of gas vapor mixture at a constant difierential pressure and thus a relatively constant fiow of gas vapor mixture will escape to atmosphere, and adequate venting will be provided at whatever pressure the system will be operating under.

It will be understood'that the invention is not to be limited to the specific construction or arrangement of parts shown, but that they may be widely modified within the invention defined by the claims.

What is claimed is:

1. In a variable pressure vent control for feedwater heaters, deaerators and the like, the combination with a vent condenser having at least one outlet for steam, air and non-condensible gas mixtures, of vent piping connected to said outlet, an auxiliary vent connected to said vent piping to allow venting of gases and vapors directly to atmosphere, a manually controlled valve in said auxiliary vent, means connected to said vent piping for controlling the pressure of said gas vapor mixture, and means connected to said vent piping coacting with said pressure controlling means for venting gases to atmosphere.

2. In a variable pressure vent control for feed water heaters, deaerators and the like, the combination with a vent condenser having at least one outlet for steam, air and non-condensible gas mixtures, of vent piping connected to said outlet, a pressure reducing valve connected to said vent piping, said pressure reducing valve constructed and arranged with a valve closing mechanism including a diaphragm, said diaphragm mounted in a chamber, a pilot line connected between said chamber andsaid vent piping on the downstream side of the said pressure reducing valve, said pilot line in combination with said diaphragm acting to maintain a constant pressure on the downstream side of the pressure reducing valve, a cap containing a restricted orifice mounted at the outlet of said vent piping and producing a restricted outlet opening for the vent piping, said orifice proportional so that it will pass the required volume of vented gas vapor mixture at a constant'differential pressure at maximum and minimum operating pressure.

3. In a variable pressure vent control for feedwater heaters, deaerators and the like, the combination with a vent condenser having an outlet for steam and non-condensible gases, of vent piping connected to said outlet, a valve in said vent piping, means in said vent piping on the downstream side of said valve for restricting the flow of steam and non-condensible gases through the downstream section of the vent piping, pressure actuated means for operating said valve, and REFERENCES CITED means connecting said pressure actuated means to time downstream side of said vent piping beg}; 332225 55 erences are of .record in the tween said valve and said flow restricting means. a

variable pressure ,vent control for feed- 5 UNITED STATES PATENTS water heaters, deaerators' and the like as claimed Number T Name Date" in claim 3 including an auxiliary vent connected 565,866 f Winkel Aug. 11, 1898 to said vent piping between the vent condenser 1,157,003 Johnson Oct. 19, 1915 and said valve, and a second valve for controlling N 1262,2251 Meyer Apr. 9, 1918 Howe! steam and non-condensible gases through 1,651,900 I Pagel 7 said auxjliary vent, 1,652,171 Hufi' Dec. 13. 1927 1,993,478 Graham Mar. 5, 1935 JOSEPH F. SEBALD. 2,366,236 Clark Jan. 2, 1945 

